Livestock enclosures require adequate ventilation and temperature control to maintain the health of the animals sheltered within such enclosures. Inadequate ventilation can lead to the spread of disease among the animals causing a loss to the operator. Stress on the animals from the lack of ventilation can slow the animal's rate of gain thus reducing the livestock producer's already slim profit margin. Livestock such as poultry are sensitive to changes in temperature and ventilation which can result in catastrophic losses if these factors are not carefully monitored and controlled.
Window vents, fans, and curtains have all been used in the past as means to control the amount of air moving through livestock enclosures. The curtains raise and lower on the sides of the livestock enclosure as part of a temperature and ventilation control system. These curtains can be raised and lowered by a power winch mechanism such as the Power Curtain controller developed by the Hired Hand Corporation. This power winch controller is a straight line frame mounted with an in-line gear motor. The motor is coupled to a thrust bearing to drive a heavy duty screw. This screw is coupled to a movable load nut which carries the curtain cables. The curtain cables are connected through a pulley system to the curtains. Limit switches at the top and bottom of the frame are activated by the movable nut to activate auxiliary devices and safety limit switches to prevent the system from malfunctioning and damaging the components.
A major disadvantage of the curtain controller system is that in order to alter the upper and lower limits of the movement of the load nut and mechanically coupled curtains, the limit switches themselves must be repositioned. The upper and lower limits of the curtains will vary with the season as well as with changes in the stage of livestock growth. There is a need in the curtain controller industry for a simple means to adjust the upper and lower limits of the ventilation curtains with as little mechanical alteration of the controller as possible.
Another disadvantage of the present controllers is that the limit switches are on the top and bottom of the controller frame. This requires that the controller be wired at the top and bottom for electrically connecting the respective switches. This increases the cost of manufacturing the controller unit as well as increasing the probability of an electrical malfunction due to excess wiring. There is a need in the livestock industry for a curtain controller with switches mounted near the bottom of the frame in close proximity to the gear motor and a source of electrical power.